This recipe comes to you courtesy of butter... The chicken Kyiv is a rich and indulgent dish; do not accept skinny substitutes, take it for what it is, a magical treat to be enjoyed occasionally!
Line two dome-shaped bowls around 7cm (2½-3") in diameter with cling film, then divide the butter between these two bowls, wrap the top with cling film, then freeze for at least 30 minutes.
Sandwich the chicken breasts between two sheets of baking parchment (one at a time) and bash them out with a rolling pin or meat mallet to an even thickness of around 10-12mm or ½".
Make sure that you only bash the underside of the breast to keep a smooth shape to your Kyiv.
Place a chicken breast on a large sheet of cling film with the smooth, un-bashed side down.
Remove the garlic butter from the cling film and place it in the centre of the chicken breast with the smaller end of the dome touching the chicken. Bring up the chicken so that the butter is completely covered, and then wrap it with the cling film.
Work the cling film with your hands to form a perfect shape that covers the butter completely and evenly at the top with a thicker layer at the base of the dome.Repeat with the other chicken breast, then refrigerate these for at least 3 hours (as long as overnight), this part of the process is essential!
Season the chicken with salt.
Now coat the chicken by rolling it in flour, then dipping it in the beaten egg and finally in the breadcrumbs. Repeat the final part of this process by double-dipping into the egg and breadcrumbs.
Place on a plate lined with baking parchment and allow to sit for 30 minutes in the refrigerator, again this process is essential.
Fill a frying pan that can be transferred to the oven with enough oil to form a 7-10mm (¼-½") layer and heat over a medium-high heat.When the oil is hot, add the Kyivs and spoon over the oil to make the breadcrumbs on top turn golden. This should take 3-4 minutes.
Transfer to the oven and cook for 20-22 minutes at 200°c or 400°F. You can check that the chicken is cooked by testing with a meat thermometer, but do this carefully so as not to burst the parcels!